Minimal example: sync_to_async threading bug (?)

This is a minimal Django application generated with django-admin startproject where only one view with an async method was added in urls.py.

Django's sync_to_async docs claim that it should schedule the given function to run in a single, shared thread no matter what, which can either be the main thread or another one (but in any case it's one and the same for different invocations):

Thread-sensitive mode is quite special, and does a lot of work to run all functions in the same thread. Note, though, that it relies on usage of async_to_sync() above it in the stack to correctly run things on the main thread. If you use asyncio.run() or similar, it will fall back to running thread-sensitive functions in a single, shared thread, but this will not be the main thread.

However, as this repository shows, in a really trivial case, invocations via sync_to_async(..., thread_sensitive=True) are scheduled in separate threads.

Steps to reproduce

1. Serve app using uvicorn --reload foo.asgi:application
2. Make a request to http://127.0.0.1:8000/myview/.
3. Make another one to the same URL within 10 seconds.
4. In the server logs, notice that the thread ID is different for each invocation of sync_to_async(f(), thread_sensitive=True)().